The Rock of Gibraltar, sometimes called the Pillar of Hercules is located in the colony of Gibraltar, off the southwestern tip of Europe on the Iberian Peninsula. This spectacular rock monolith covers a land area of about six square kilometers and overlooks the African coast.The inside of the Rock is criss-crossed by a great and complex system of underground fortifications, known as the Great Siege Tunnels. The tunnel system was expanded and the Rock became a keystone in the defense of shipping routes to the Mediterranean.On many occasions over the centuries Gibraltar has proved impervious to attack. Despite long sieges it seemed that there was nothing that could destroy the Rock or her people. This history has inspired the simile ‘solid as the Rock of Gibraltar’, which is used to describe a person or situation that cannot be overcome and does not fail. The motto of the Royal Gibraltar Regiment, Nulli Expugnabilis Hosti, reflects this famous invincibility; it is Latin for ‘Conquered by No Enemy’.